Toggle mechanism for a circuit breaker



Nov. 19, 1968 5. 5. HARPER 3,412,351

TOGGLE MECHANISM FOR A CIRCUIT BREAKER Filed April 26, 1966 4Sheets-Sheet 1 INVENT OR 64 64 George 5. Harper OR NEYS Nov. 19, 1968 c.s. HARPER TOGGLE MECHANISM FOR A CIRCUIT BREAKER Filed April 26, 1966 4Sheets-Sheet 2 9 llllil 6 IN VE NTOR George 5. Harper BY 22%,WM;

ATTORNEYS Nov. 19, 1968 G. s. HARPER 3,412,351

TOGGLE MECHANISM FOR A CIRCUIT BREAKER Filed April 26, 1966 4Sheets-Sheet 5 FIG. 3.

INVENTOR George .S. Harper ORNEYS Nov. 19, 1968 G. s. HARPER 3,412,351

TOGGLE MECHANISM FOR A CIRCUIT BREAKER Filed April 26, 1966 4Sheets-Sheet 4 FIG. 4.

INVENT OR Gear 8 .5. Har er FIG. 9. g p

ORNEYS United States Patent ABSTRACT OF THE DISCLOSURE A togglemechanism for circuit v breakers including first and second pivotallymounted levers which are operatively connected through a pair of pivotallinks. Means are provided on the links for locking them against pivotalmovement with respect to each other. Further means are provided tounlock the locking means to permit relative pivotal movement to therebyeffect the tripping of the mechanism.

This invention relates to a circuit breaker and toggle mechanismtherefor and is a continuation-in-part of the circuit-breaker mechanismdisclosed in my copending application Ser. No. 377,993 filed June 25,1964, now Patent 3,251,232, relative to its application to circuitbreakers of greater capacity.

It is a further object of this invention to provide a simplified linkagewhich will withstand the shock and vibration without tripping whensubjected to environmental conditions causing violent stresses on thecircuit breakers.

These and other objects of the invention will be manifest from thefollowing description and accompanying drawings wherein:

FIG. 1 is a perspective view of the inventive circuit breaker in itshousing;

FIG. 2 is a view with one side of housing removed showing the mechanismin relatched open position where the contacts are open;

FIG. 3 is a partial sectional view showing the mechanism in a positionwhere the contacts are closed;

FIG. 4 is a partial sectional view showing the mechanism in anintermediate or tripped open position;

FIG. 5 is a section along the line 55 of FIG. 2;

FIG. 6 is an enlarged section on the line 6-6 of FIG. 2 but showing thethreaded holding ferrule in place;

FIG. 7 is an enlarged detail of the sear pin and striker bar assembly;

FIG. 8 is a detail view of the engagement of the sear pin and strikerbar assembly in engagement with the forked lever; and

FIG. 9 is a detail of the electromagnet armature bell crank assembly.

In the housing 10, which is formed of a molded plastic of goodelectrical insulation properties, is supported a frame 11 upon which ismounted the operating elements of the circuit breaker to move themovable contact 12 into and out of engagement with fixed contact 13.

The movable contact is secured to a lever 14 pivotally and slidablymounted on the frame by a pin 15 and an elongated opening 16. Pin 15 ismounted in the frame 11 intermediate the ends while the ends extendbeyond the frame and fit snugly into recesses 17 molded in the housingportions and 10' as seen in FIG. 5. A spring 18 is wound around the pinand is provided with a biasing arm 19 bearing against the lever 14 and areaction arm 20 bearing against the frame 11. Portions of the frame 11have been omitted from FIGS. 3 and 4 for the sake of clarity. The entireframe 11 is shown in FIG. 2.

An actuating lever 21 is pivotally mounted on the frame 11 by a pin 22.The pin 22 is mounted in the frame intermediate the ends while the endsextendsbeyond the frame and fit snugly into recesses 22 molded in thehousing 10 (as seen in FIG. 5). A spring 23 is wound around the pin 22and has a biasing arm 24 bearing against a pin 25 and a reaction arm 26bearingagainst the frame 11.

An L-sh'aped link 27 is pivotally mounted on pin 25 and is pivotallyconnected to a speced pair of links 28 by a pin 29. The links 28 arepivotally connected by a pin 30 to straddle the lever 14.

A shaft of sear pin 31 is rotatably supported in link 27 at the #bend ofthe L and is provided with a reduced section 32 between the links whichresults from grinding .a flat surface 32 on shaft 31 (FIG. 7) which actsas a sear for edge 42 of forked member 40. An arm or striker bar 33 ismounted rigidly and nonrotatably on shaft 31 and carries a tab 34 bentup from the end of the arm. The end of shaft 31 is square to accommodatethe square hole in arm 33. After assembly, the end of shaft 31 is peenedtight against arm 33 thus permanently keying the shaft and arm together.A spring 35 is wound around shaft 31 and is provided with arms 36 arid37 bearing respectively against a stop 38 integral with, one arm of link27 and against an extension 39 of arm 33. The spring is wound to urgethe extension 39 against the stop 38.

A forked member 40 is pivotally mounted on pin 25 between the parallelarms of link 27. One leg 41 of the fork is provided with an edge portion42 for engagement with the sear portion 32 of shaft 31, and the otherleg 43 of the fork is provided with a curved cam section 44 forengagement with a pin 45 carried by links 28. Between the legs at theend of cam section 44 is a locking recess 46.

The frame 11 is provided with a shelf 47 on which is mounted anelectromagnet 48 having a winding, one end of which is connected inseries with terminal 49 and the other end in series with a braided,flexible copper wire 50 secured to lever 14, movable contact 12,;fixedcontact 13, contact support 51 and terminal 52. Anfarmature 53 ispivotally mounted on the frame by a pin 54 and is integral with anarmature lever 55 to forni' therewith a bell crank 56. Spring 57 ismounted on pin 54 to bias the bell crank 56 towards the position shownin FIG. 2. The free end of the armature lever forms an arcuate triggercam surface 58. In the closed contact position, the linkage is in theposition shown in FIG. 3 with the tab portion 34 adjacent the arcuatetrigger cam surface 58 at the end of armature lever 55.

On overload the electromagnet 48 is energized to attract armature 53 topivot armature lever 55 bringing the trigger cam surface 58 into contactwith tab 34 to rotate striker bar 33 and shaft 31. Rotation of the shaft31 presents the reduced section 32 to the edge 42 of the fork 40,allowing the fork 40 to rotate counterclockwise about pin 25 to releasepin 45 from recess 46, as illustrated in FIG. 4. The release of pin 45allows the linkage to collapse and the lever 14 to pivot about pin 15 toseparate the contacts 12 and 13. The are drawn by the separatingcontacts is extinguished by its reaction to the arc chutes 59 and 60 inthe usual manner. Vent opening 67 is provided in the casing 10 closelyadjacent the arc chutes and serving as a pressure release for the gasesproduced by arcing. The force of spring 23 reacts against pin 25 torotate the lever 21 to the position shown in FIG. 2. The movement of pin25 about pin 22, under the urging of spring 23, realigns links 27 and 28and fork element 40 to replace pin 45 in recess 46 as shown in FIG. 2.In order to close the contacts, the handle is rotated clockwise aboutpin 22 to force the linkage down to rotate lever 14. When the contactsclose, they become a pivot about which lever 14 is rotated against theforce 3 of spring 18 to load the spring and linkage for future toggleaction.

The housing is formed of two mirror-image sections 10 and 10 (FIGS. 1and 5) which are secured together by rivets 62 passing through openingsin the housing. One of the sections, such as 10, is provided with 'anelongated groove 70, and the other section is provided with an elongatedtongue which is snugly received in the groove. This tongue-and-groovearrangement is for the purpose of accurately aligning the housingsections on assembly.

Each housing section is provided with recesses 63 molded in the meetingfaces. The recesses 63 are provided with enlarged hexagon-a1 portions64. When the sections are secured together as shown in FIG. 5, therecesses 63 combine to provide openings which receive threaded metalferrules 65 (FIG. 6) with hexagonal heads by which the assembly issecured to a support. Therecesses 66 combine to provide openings for thereception of the threaded terminals 49 and 52.

What is claimed is; s r Y 1. A circuit breaker comp-rising a housing ofmolded plastic electrical insulating material, said housing havingspaced recesses therein, a frame in said housing, a pair of spaced pinsmounted in said frame and extending through the frame and into saidrecesses, a fixed contact and a movable contact in said housing, atoggle mechanism for moving said movable contact into and out of contactwith said fixed contact, said toggle mechanism comprising a first leverpivotally and slidably mounted on said frame and carrying said movablecontact, a handle 4 mounted on said'frame and having a portion extendingoutwardly of said housing, a pair of links pivotally connected to eachother and to said contact lever and handle respectively, means forlocking said pair of links against pivotal movement with respect to eachother, and means for unlocking said means to permit pivotal movement ofsaid pair of linles with respect to each other, said locking meanscomprising a forked lever pivotally mounted on said frame, a pin carriedby oneof said pair of links for reception in the fork of said forkedlever, a sear on said frame for holding said forked lever againstpivotal movement, said unlocking means including a. solenoid andarmature responsive to a predetermined current flow through saidsolenoid for tripping 'saidsear.

2. A circuit breaker according to claim 1 wherein said forked lever ispivotally connected to said handle.

3; A circuit breaker according to claim 1 wherein said fixed contact ismounted on a substantially U-shaped support, said support having one armcarrying said fixed contact spaced inwardly from said housing.

References Cited UNITED STATES PATENTS 3,056,008 9/1962 Schwartz 335383,329,912 7/1967 Brackett 335- 3,329,913 7/1967 Camp 335174 BERNARD A.GILHEANY, Primary Examiner.

H. BROOME, Assistant Examiner.

